British officials say Prince William's wife, Kate, has given birth to a baby boy, the couple's first child and the heir to the British throne.

Officials say the boy was born Monday afternoon and weighs 3.8 kilograms .

The Duchess of Cambridge was admitted to St. Mary's Hospital early Monday, with hundreds of international media camped outside.

The child will displace Prince Harry as the third in line to the throne, coming behind Queen Elizabeth's eldest, Prince Charles, and his son, Prince William.

Under a new law, still to be enacted by Britain's parliament, the child would have been heir to the throne even if it was a girl. For centuries, preference was given to male heirs, so a first-born princess could be overtaken in line by a younger brother.